Regression Testing in Software Testing: Definition and Best Practices for 2024

Making sure your apps work properly as they get updated and new features are added is crucial. This blog delves into regression testing, a methodical approach designed to ensure that new changes do not disrupt existing functionalities. We'll define regression testing, discuss why it’s important in modern Agile and DevOps environments, and look at some of the best practices for integrating it into your development workflow. Additionally, we’ll highlight the latest trends and tools in regression testing for 2024, providing a comprehensive guide for QA engineers and developers striving to deliver the best software.

What is regression testing?

Regression testing in software development is the process of re-running existing tests on a software application after a change has been made. This change could be a bug fix, a new feature, or even a minor code tweak. The core purpose of regression testing is to ensure that the changes haven't unintentionally broken any existing functionality. 

Think of it like this—imagine you built a house and thoroughly tested all the plumbing, electrical wiring, and doors. Now, you want to add a new room. Regression testing is like going back and checking all the original plumbing, wiring, and doors to make sure they still work after the new room is built.

Here are some key things to remember about regression testing:

• Tests are created beforehand. Before any changes are made, you need a set of tests that verify how the software is supposed to function. And to do so, you need to write an effective test case.
• The focus is on existing functionality. Regression testing isn't about checking the new changes, but ensuring that the existing features haven't been affected.
• Triggered by change. Regression testing is typically run whenever the software is changed, such as a bug fix, new feature addition, or configuration adjustment.

By regularly performing regression testing, QA engineers and developers can catch bugs early on and ensure that the software's overall quality and stability remain consistent with each update.

Why does regression testing matter in software development?

Regression testing acts as a safety net, ensuring that new features and code changes don't accidentally break existing functionalities. It plays a critical role by:

Accommodating Agile workflows

The current software development landscape uses Agile and DevOps methodologies that prioritize frequent updates and releases. By systematically re-running existing tests after each change, QA engineers can ensure that the breakneck speed of development doesn't compromise on software quality. Catching bugs early in the product development cycle prevents them from snowballing into bigger issues later on, allowing for a more stable product despite frequent updates. 

Mitigating risks in complex systems

Software applications are often intricate webs of interconnected functionalities. A seemingly minor tweak in one part of the codebase can have unforeseen consequences elsewhere. Regression testing safeguards against these ripple effects by systematically re-running tests that verify individual functionalities and how different parts of the system interact. This testing approach helps expose issues that could cause unexpected disruptions in how the system behaves. By ensuring that these integrated functionalities continue to work together, regression testing helps prevent regressions that could cripple core functionalities and hinder the overall performance of the system.

Ensuring a great user experience

Regression testing ensures a great user experience by verifying that new updates and changes do not disrupt existing functionalities. By re-running tests on previously validated features, it identifies and resolves any issues that might have been introduced with new code. This helps maintain the stability and reliability of the software, ensuring that users can continue to enjoy a seamless and predictable experience. Consistent regression testing minimizes the risk of bugs and glitches, which can frustrate users and diminish their trust in the application. By catching and addressing these problems early, regression testing contributes to a smoother, more reliable user experience.

Optimizing development costs

The earlier a bug is identified, the cheaper it is to fix. Regression testing helps unearth issues early in the development cycle before they become major roadblocks. This proactive approach saves time and resources compared to fixing critical issues discovered later in the development process or even after release, potentially requiring patches and hotfixes.

Increase efficiency with CI/CD pipeline

Automation is a cornerstone of modern development workflows. Regression testing can be seamlessly integrated into CI/CD pipelines, enabling automated testing with every code change. This streamlines the development process by automatically identifying and addressing bugs as they arise, allowing QA engineers to focus on more strategic tasks.

Example of regression testing in practice

Imagine you're a QA engineer working on an e-commerce website. You've recently implemented a new feature that allows users to filter products by color. Let’s see how you can perform regression testing to ensure existing functionalities aren't broken:

Step 1: Create test cases

Define test cases following best practices that cover various aspects of the website's existing functionalities, like adding items to the cart, logging in, and completing a purchase.

Step 2: Execute test cases 

Run existing test cases to verify if everything still works as expected. This might involve adding items to the cart from different categories (clothing, electronics, etc.), logging in with different user accounts, and simulating the entire checkout process.

Step 3: Analyze results 

Compare the expected outcome with the actual outcome. The expected outcome is that all existing functionalities work flawlessly, even with the implementation of the new filter feature. Being able to add items, log in, and complete a purchase should function uninterruptedly regardless of the color filter being used.

Benefits of regression testing in this example

• Early bug detection. By proactively testing existing functionalities, you can catch any bugs introduced during the development of the new color filter feature. This allows for quicker fixes before the update goes live.
• Reduced risk of regressions. Regression testing minimizes the risk of the new feature causing regressions or breaking parts of the website that were previously working correctly. 
• Improved software quality. By ensuring existing features remain functional, regression testing ensures that both new and existing features work seamlessly together, enhancing the overall quality and reliability of the software, leading to a better user experience and increased customer satisfaction.

Automated regression testing

Regression testing can be automated using various tools, saving time and resources for testers and QA engineers. The scope and frequency of automated regression testing depend on the complexity of the software and the pace of development. Choosing the right tools and frameworks can significantly enhance your automated regression testing efficiency. Here's a breakdown of some popular options:

Web app testing

Selenium: A pioneer in web automation testing frameworks, Selenium offers extensive support across various programming languages and browsers. Though it requires coding knowledge, its flexibility makes it a powerful tool for complex testing scenarios.

Cypress: This modern JavaScript framework is gaining traction for its user-friendly approach. Cypress offers a visual test recorder that simplifies script creation for common web testing tasks. It's a great option for testers who want a balance between ease of use and coding control.

Playwright: This newcomer from Microsoft is gaining attention for its speed and reliability. Playwright excels in cross-browser testing and can be a valuable asset for teams working on complex web applications.

Puppeteer: A Node.js library developed by Google, Puppeteer offers powerful control over headless Chrome or Chromium browsers. This makes it a great choice for advanced web application testing and scraping tasks.

Mobile app testing

Appium: The go-to open-source framework for mobile app testing, Appium allows you to automate tests across various mobile platforms (iOS, Android). It supports native, hybrid, and mobile web applications, providing comprehensive testing capabilities.

Maestro: The Maestro framework is a mobile UI automation tool that simplifies the process of testing mobile applications. It is particularly user-friendly due to its declarative scripting approach using YAML, making it easy to write and maintain test scripts.

Cross-platform testing

BrowserStack Automate: This cloud-based platform integrates with popular testing frameworks like Selenium, Cypress, Playwright, and Puppeteer. It enables developers and QA teams to execute automated tests across a wide array of real browsers, devices, and operating systems concurrently, mimicking real-world user conditions for comprehensive testing.

Choosing the right tool

The right tool for you depends on your specific needs. When choosing a tool for regression testing, consider factors like:

• Project type. Are you testing web, mobile, or API applications?
• Technical expertise. Does your team have extensive coding experience or do you need a more user-friendly option?
• Budget. Open-source tools offer cost-effectiveness, while commercial options might provide additional features and support.

But remember, regression testing is more than just the tools—you should think about your testing strategy. An effective QA strategy involves:

1. Creating clear and comprehensive test cases. Write a set of tests that cover all critical functionalities of your application.
2. Integrating regression testing into your CI/CD pipeline. Automate regression testing as part of your development process to catch bugs early and often.
3. Analyzing test results and taking corrective action. Review test reports, identify bugs, and prioritize fixes to maintain software quality.

By understanding the available tools, crafting a strategic testing plan, and implementing these tools effectively, you can ensure your software remains robust and reliable after every update.

Regression testing techniques you should know

Adding regression testing to an established project doesn't require a complete overhaul. Here are different techniques you can leverage:

Start small with unit regression testing. This is a beginner-friendly approach that provides a high-level overview of the code. Imagine having a checklist of key functionalities to verify after each change. This is an excellent entry point for regression testing in mature projects.

Prioritize with partial regression testing. Break down the project into logical modules that work together seamlessly.  Focus your regression efforts on the most critical functionalities within these modules. For the remaining modules, you can perform unit regression testing. This targeted approach balances efficiency with coverage.

Comprehensive testing for new projects, a.k.a. complete regression testing. This is the most thorough approach, involving a detailed analysis of the entire codebase to identify all functionalities that could be impacted by changes. While time-consuming, it's highly beneficial if implemented from the very beginning of a project's development lifecycle

The state of regression testing in 2024: Emerging trends

Regression testing in 2024 focuses more on automation, efficiency, and leveraging advancements in artificial intelligence (AI) and machine learning (ML). Here are some emerging trends to watch out for:

1. AI integration

The future of regression testing is being significantly shaped by the integration of AI and machine learning technologies. These advancements enable more intelligent and efficient testing processes by predicting the areas of the codebase that are most likely to contain defects. AI-driven regression testing tools can analyze past test execution data, identify patterns, and optimize the selection of test cases to maximize coverage while minimizing redundant tests. Machine learning models can also automate the maintenance of test scripts, adapting them to changes in the application without human intervention, thus reducing the overhead associated with keeping tests up-to-date.

2. Shift-left testing and continuous integration

Shift-left testing, where testing activities start early in the development lifecycle, combined with continuous integration (CI) practices, is becoming a cornerstone of modern regression testing. By integrating regression tests into the CI/CD pipeline, teams can identify and address defects as soon as they are introduced into the codebase. This approach not only improves the overall quality of the software but also accelerates the development process by ensuring that bugs are caught early when they are cheaper and easier to fix. Tools that facilitate seamless integration of regression tests into CI/CD pipelines are becoming essential for maintaining rapid and reliable release cycles.

3. Test automation frameworks and tools

The evolution of test automation frameworks and tools continues to drive the efficiency of regression testing. Modern tools are designed to support a wide range of programming languages and platforms, offering more flexibility and scalability. These tools provide advanced features such as visual test creation, robust reporting, and comprehensive dashboards that enhance the visibility of testing efforts. Additionally, the emergence of low-code and no-code automation tools is democratizing test automation, enabling non-technical team members to contribute to the creation and maintenance of regression tests.

4. Cloud-based testing environments

Cloud-based testing environments are transforming how regression testing is conducted by providing scalable, on-demand infrastructure. This trend allows QA teams to run large test suites in parallel, significantly reducing the time required for regression testing. Cloud platforms, like Loadero, offer the flexibility to test across multiple configurations and environments, ensuring broader coverage and more reliable results. The pay-as-you-go model of cloud services also makes it more cost-effective for organizations to scale their testing efforts according to project needs, without the overhead of maintaining physical infrastructure.

5. Enhanced collaboration and DevOps practices

Enhanced collaboration and the adoption of DevOps practices are driving more integrated and efficient regression testing processes. DevOps emphasizes the importance of communication and collaboration between development and operations teams, which extends to testing. Tools that facilitate real-time collaboration, such as shared dashboards and integrated development environments (IDEs) with built-in testing capabilities, are becoming increasingly popular. These tools help ensure that regression testing is not a siloed activity but an integral part of the entire development process, leading to faster feedback loops and higher software quality.

By staying informed about these emerging trends and utilizing the right tools and strategies, organizations can achieve efficient and effective regression testing, ensuring the quality and stability of their software throughout its lifecycle.

The bottom line

Regression testing remains a cornerstone of software quality assurance, ensuring that new code changes do not introduce errors into existing functionalities. By leveraging advanced tools and methodologies such as AI-driven testing, continuous integration, and automated frameworks, teams can efficiently identify and address potential issues early in the development cycle. This proactive approach not only enhances software stability and user satisfaction, but also optimizes development costs by catching bugs before they escalate into larger problems. As the landscape of software development evolves, staying abreast of emerging trends and integrating robust regression testing practices will be essential for maintaining high-quality, reliable software products.

Looking to improve your software testing efforts and streamline your QA processes? We can help. Contact us to learn more about our software testing services and how they can benefit your project.